Remove internal `Xamarin.Utils.*` types from platform assemblies (#11811)

Only the `SanitizeObjectiveCName` method _can_ be needed, by the
registrar. However if marked then the `StringUtils:.cctor` will also be
marked, including the data (`static char[]`) which is not needed for apps

Moving `SanitizeObjectiveCName` to the `Registrar` type is simpler and
solve (removes) the extra cost (baggage) from the app.

src/ObjCRuntime/Registrar.core.cs

@@ -1,3 +1,4 @@
+using System.Text;
 
 namespace Registrar {
 	abstract partial class Registrar {
@@ -12,5 +13,38 @@ namespace Registrar {
 				first = (char) (first - 32 /* 'a' - 'A' */);
 			return "set" + ((char) first).ToString () + getterSelector.Substring (1) + ":";
 		}
+
+		public static string SanitizeObjectiveCName (string name)
+		{
+			StringBuilder sb = null;
+
+			for (int i = 0; i < name.Length; i++) {
+				var ch = name [i];
+				switch (ch) {
+				case '.':
+				case '+':
+				case '/':
+				case '`':
+				case '@':
+				case '<':
+				case '>':
+				case '$':
+				case '-':
+					if (sb == null)
+						sb = new StringBuilder (name, 0, i, name.Length);
+					sb.Append ('_');
+					break;
+				default:
+					if (sb != null)
+						sb.Append (ch);
+					break;
+				}
+			}
+
+			if (sb != null)
+				return sb.ToString ();
+
+			return name;
+		}
 	}
 }

src/ObjCRuntime/Registrar.cs

@@ -22,10 +22,10 @@ using System.Text;
 
 using Foundation;
 using ObjCRuntime;
-using Xamarin.Utils;
 using Xamarin.Bundler;
 
 #if MTOUCH || MMP || BUNDLER
+using Xamarin.Utils;
 using TAssembly=Mono.Cecil.AssemblyDefinition;
 using TType=Mono.Cecil.TypeReference;
 using TMethod=Mono.Cecil.MethodDefinition;
@@ -437,7 +437,7 @@ namespace Registrar {
 						throw new InvalidOperationException ();
 					var attrib = CategoryAttribute;
 					var name = attrib.Name ?? Registrar.GetTypeFullName (Type);
-					return StringUtils.SanitizeObjectiveCName (name);
+					return SanitizeObjectiveCName (name);
 				}
 			}
 
@@ -447,7 +447,7 @@ namespace Registrar {
 						throw new InvalidOperationException ();
 					var attrib = Registrar.GetProtocolAttribute (Type);
 					var name = attrib.Name ?? Registrar.GetTypeFullName (Type);
-					return StringUtils.SanitizeObjectiveCName (name);
+					return SanitizeObjectiveCName (name);
 				}
 			}
 
@@ -2600,7 +2600,7 @@ namespace Registrar {
 			}
 			if (name == null)
 				name = GetTypeFullName (type);
-			return StringUtils.SanitizeObjectiveCName (name);
+			return SanitizeObjectiveCName (name);
 		}
 
 		protected string GetExportedTypeName (TType type)

src/frameworks.sources

@@ -1842,7 +1842,6 @@ SHARED_CORE_SOURCES = \
 
 SHARED_SOURCES = \
 	../runtime/Delegates.generated.cs \
-	../tools/common/StringUtils.cs \
 	MonoNativeFunctionWrapperAttribute.cs \
 	NativeTypes/NMath.cs \
 	ObjCRuntime/AdoptsAttribute.cs \

src/generator.cs

@@ -6412,7 +6412,7 @@ public partial class Generator : IMemberGatherer {
 				if (!string.IsNullOrEmpty (model.Name)) {
 					register_name = model.Name;
 				} else if (model.AutoGeneratedName) {
-					register_name = StringUtils.SanitizeObjectiveCName (GetAssemblyName () + "__" + type.FullName);
+					register_name = Registrar.Registrar.SanitizeObjectiveCName (GetAssemblyName () + "__" + type.FullName);
 				}
 			}
 			Header (sw);

tools/common/StringUtils.cs

@@ -221,39 +221,6 @@ namespace Xamarin.Utils {
 				return new Version (major, 0);
 			return Version.Parse (v);
 		}
-
-		public static string SanitizeObjectiveCName (string name)
-		{
-			StringBuilder sb = null;
-
-			for (int i = 0; i < name.Length; i++) {
-				var ch = name [i];
-				switch (ch) {
-				case '.':
-				case '+':
-				case '/':
-				case '`':
-				case '@':
-				case '<':
-				case '>':
-				case '$':
-				case '-':
-					if (sb == null)
-						sb = new StringBuilder (name, 0, i, name.Length);
-					sb.Append ('_');
-					break;
-				default:
-					if (sb != null)
-						sb.Append (ch);
-					break;
-				}
-			}
-
-			if (sb != null)
-				return sb.ToString ();
-
-			return name;
-		}
 	}
 
 	static class StringExtensions